This invention is concerned with therapeutic irradiation of lesions in organs or lumina of mammalian patients, especially humans.
Therapeutic delivery of radiation therapy to many organs, lumina, and systems within the body using radioactive isotopes is well known. Presently, radiation therapy is directed to tissue within an organ system of the body that permits the introduction of the device to both target and treat; examples of routes that could be used are the gastrointestinal tract and all its tributaries, i.e. the common duct hepatic duct and the pancreatic duct, the urinary tract and its tributaries, i.e. the urethra and ureter providing access to the kidney and all distal organ systems of the urinary tract, the vascular system including the lymphatic system, which will provide access to any organ system in the body including the integument, the neurological, the endocrine, the pulmonary, the musculoskeletal and the hematopoietic systems. This list should not be considered complete because of other points of access to all areas of the body via a percutaneous or transvisceral route specific portions of the alimentary, biliary, vascular, neurological, gynecologic, and urinary systems. Traditionally, therapeutic radiation is generated by large units operating outside the patient and is a beam of radiation directed to specific anatomy. If the beam is omni directional, shielding of non-diseased areas adjacent to the anatomy to be treated is required. In order to avoid damaging exposure to areas of the patient's skin and other tissue leading to the target region, multiple beams of radiation may be directionally administered so as to intersect at the lesion or abnormality being treated. These beams may be applied simultaneously or sequentially, such that the prescribed dose is applied to the tumor, but lesser radiation is applied to normal tissue. Irradiation using such intersecting, externally-applied beams is sometimes known as intensity modulated radiation therapy, or IMRT.
In some instances, radioisotopes are used within organs and lumina within the body in an effort to more directly treat diseased tissue. Because of the isotropic nature of the radiation emitted by radioisotopes, however, present methods of internal treatment may require the therapist to compromise in preparing treatment plans in order to prevent damage to normal tissue adjacent to the target lesions, but still effectively treat the lesion. The potential for serious complications exists. Thus, treatment of the abnormalities is often times compromised resulting in less than optimal therapy to the tumor itself. In addition, use of radioisotopes has attendant radiation safety concerns for therapeutic personnel. The practical effect of these limitations and concerns is that both externally and internally applied treatment modalities lack optimal targeting specificity, and are less focused on the tumor than desired. As a consequence, normal tissue is damaged.
In view of the shortcomings of the methods described above, there is a need for apparatus and methodology for delivery of a controllable, more finely focused radiation therapy. It is therefore an object of this invention to enable the therapist the ability to accurately direct the radiation therapy at the lesion according to an optimal plan, either by manual control of the radiation source, aided by direct visualization of the target area during the treatment process, or by using automated control methods. It is a further object of this invention that radiation risk to both the therapist and the patient be minimized during the treatment process.